Hello...I have to agree with Donna that RCL would be the better choice with kids. It might be the better choice even if you did not have the kids with you. WE have been on both cruise lines several times and it's just a matter of opinion of which one you would prefer if without kids. However, with the Voyager class ships, there are so many things for kids compared to Princess which caters a bit more to an older age group. And on the Voyager ships, you have that open Promenade floor with shops, cafes, and of course the two nightlyh parades which the kids should love.
As far as the itinerary is concerned, we are dong the same itinerary this October to the Southern Caribbean on the Adventure Of The Seas. Have done the Southern before but not with Curacao included, so we are looking forward to it. We totally love Aruba and hear Curacao is wonderful too.
If you need more info on the islands, I would be more than happy to help further after we get back from our cruise, so if you have anyh other questions, let me know in advance and I will make sure I have the answers for you when we get back.